Soil probing devices are known in various embodiments. For example EP 0 989 240, that was filed in the name of the present applicant, shows a soil probing device that has two sets of clamping members that can be moved up and down independently from each other and that are designed to alternately clamp a probing rod and push it gradually into the ground. Cone penetration measurements are performed during this penetration for determining the desired geophysical and geotechnical properties of the soil. The soil probing device can be supported directly onto a piece of land via a frame or can be mounted on a vehicle like a caterpillar-type. It can also be used for carrying out penetration measurements underwater, for example on a sea bed, provided that it is equipped with a special underwater drive unit. During penetration, the two sets of clamping members are controlled such that a first one of them gets moved down in a clamping position while taking the probing rod with it and pushing it into the ground, whereas a second one at the same time gets moved up along the probing rod in a release position. As soon as the first clamping set starts to reach its lowermost position, both clamping sets are controlled to switch functionality, that is to say that the second one then takes over the clamping of the probing rod and starts to push it further down into the ground, while the first one gets moved up along the probing rod in a release position. Thus the probing rod can be pushed in one continuous go into the ground. The probing rod here is formed by a measuring probe at its forward end and a plurality of distinctive straight rod sections of limited length that get connected thereto. With this, the rod sections are connected to one another by means of engageable male and female screw thread connections that are provided at free outer ends of the rods.
A disadvantage with this known device is that the picking and placing of new rod sections and screwing them onto the probing rod is time-consuming and difficult to automate, particularly when it is desired to perform the screwing of a new rod section to the probing rod at the same time that this probing rod is forced to penetrate at a constant speed into the ground in one continuous go. Another disadvantage is that the device requires a lot of space and that it may occur that one accidentally tries to place a new one of the rod sections onto the probing rod while this new rod section is wrongly positioned with its male and female locking parts. Yet another disadvantage is that during a removing of the probing rod out of the ground again, the unscrewing of the rod sections and then placing them in a storage facility also is time-consuming and difficult to automate
Another known soil probing device that has been successfully commercialized for several years in the market by applicant under the trademark “Roson[,]” comprises a frame inside which two rotatable gripping wheels are provided as drive means. Those gripping wheels are positioned opposite one another. A probing rod is guided with a tight fit in between the gripping wheels. A rotating of the gripping wheels then forces the probing rod to penetrate in one continuous go into the ground. When to be used offshore for measurements on sea floors, it is known for this device to preassemble lengths of probing rod of up to 40 meters out of a plurality of rod sections inside an evenly long support mast that is placed upright on deck of or on-board of a ship. Subsequently the soil probing device together with the support mast and the preassembled length of probing rod inside it, gets lowered to the sea floor and there can start to perform a penetration test.
A disadvantage with this is that the preassembling of the probing rod on the ship is time-consuming and makes the operational costs for the ship expensive. Furthermore the preassembling process of the probing rod is sensitive for weather conditions and swells. Also the assembly of the preassembled probing rod and support mast is vulnerable because of its great length, not only during the preassembly process itself but also during its lowering towards the sea floor, which can be more than 2000 meters below. Further it is disadvantageous that a heavy winch is needed for lowering the assembly to the sea floor, while at the same time means need to be provided for keeping the support mast and the preassembled probing rod in an upright position.
WO 00/17481 tries to overcome those disadvantages by no longer making use of distinctive straight rod sections, but by making use of a semi-rigid elongate probing rod that is wound in one piece onto a large diameter storage wheel. During penetration the elongate probing rod then can be gradually unwound from the wheel and forced to penetrate into the ground by suitable drive means, that here are formed by endless caterpillar-like engaging elements.
A disadvantage with this however is that the probing rod during its unwinding of the large diameter storage wheel needs to be plastically deformed such that it gets straight. When the penetration process is completed, and the probing rod needs to be pulled out of the ground, the probing rod again needs to be plastically deformed such that it can be wound back again on the large diameter storage wheel. Those repeated plastic deformations make it necessary to have the probing rod replaced after a limited number of usages. This makes this type of soil probing device costly. Another disadvantage is that the required plastic deformation makes it necessary to use a relative slender elongate probing rod, because otherwise the plastic deformation would become too difficult. In particular, with this type of elongate probing rod in one piece, a diameter of 19 mm is known to be used, whereas for probing rods composed out of distinctive rod sections, on almost twice as large diameter of 36 mm is more common However such a relative slender probing rod has limited strength and limits the maximum penetration depth. Also it entails the risk that it may start to plastically deform and deviate from its aimed vertical penetration path when running against obstacles.